The calorie goal

puterchickfl

So I'm a bit confused on what my calorie goal at the end of the day should be. For example, lets say I am on a 1800 calorie diet. This means I have to eat that many calories for the day, correct? And lets say I put in some exercise and burn 500 calories. When I add foods to the diary, it subtracts from it and when i exercise it adds to it. So what should be my ending number? I'm always under my calorie goal for the day and I'm just very confused by this???